1. Field of the Invention
The present invention relates to an in-mold label with a separable part, which is stuck to a thermoplastic resin container produced in a mode of differential pressure molding or blow molding, simultaneously with the production of the container.
2. Description of the Related Art
Known are some in-mold labels that are used in an in-mold process in which a label is previously set in a mold and then a thermoplastic resin is introduced into the mold and molded into a container in a mode of injection molding, blow molding, differential pressure molding or foam molding while, at the same time, the label is stuck to the container produced (see JP-A 58-69015, and EP-A 254,923).
As one example of such labels, proposed is an in-mold label with a separable coupon ticket or the like (see JP-A 6-51701, 6-95593, 6-308886). Some methods have been proposed for designing such a label with a separable part in order that the purchaser who has bought a labeled product can readily tear off the separable part from the label. For example, the separable part is partitioned from the label body by perforations along which the part is to be torn off, and further the amount of the adhesive on the back side of the separable part is reduced (see U.S. Pat. No. 5,172,936), or no adhesive is applied to the separable part.
However, the label with such a separable part has a drawback in that the separable part is readily loosened from the surface of the labeled container. For example, when resin containers labeled with it and filled with contents receive some shock applied thereto while they are transported or put on a display stand, or when some load is given to the resin containers in order to squeeze out the contents, then the separable part may be readily loosened from the labeled container owing to the shock or the load applied thereto. On the other hand, if the amount of the adhesive given to the separable part is too much increased in order to prevent the part from being loosened, it may cause another problem in that, even though the separable part partitioned from the label body by tearing perforations around it, the part could not be well torn along the perforations and therefore could not be satisfactorily separated from the label body.
When the separable part is used as a coupon ticket, then it may be desired that not only the surface of the separable part but also the back side thereof that is to adhere to containers is printed. However, when the back side is subjected to surface activation treatment in order that it is well compatible with printing ink and when it is printed with printing ink, then the adhesiveness between the separable part and the labeled container may be greatly lowered and therefore there occurs a problem in that the separable part is readily loosened from the surface of the labeled container.